The present invention relates to apparatus and equipment for continuously and electrically-resistively heating elongated stock having a definite end and a definite beginning and being made of electriclaly conducted material such as metal tubes, pipes, wires, rods, etc.
Heating elongated stock while it passes through a heating station and by means of electrically resistively heating is known in a variety of configurations. It is of course necessary to conduct current into and from the stock in sliding or rolling contact fashion, as the stock passes through. If the stock, for example, is a split tube, the heating may involve only the edges, (see e.g., German Pat. No. 551,180), otherwise care must be taken to distribute the current more or less evenly in the stock. It is, however, more or less inherent in such a system that the electrodes must be spaced-apart because certain length of resistive material of the tube are needed as electrical resistance between the electrodes which otherwise would be short-circuited. It was found, however, that the known equipment does not provide for sufficient heating of the beginning and end portions of such stock. Actually, the front end and the rear end of a tube or rod or the like remains cold. If this heating device is provided for purposes of preheating stock prior to being hot or warm rolled, then it is necessary to cut off the cold ends before the stock is fed to the rolling mills. This, of course, is a cumbersome procedure. The situation is similar in the case of welding where end portions of a split tube are insufficiently welded and have to be cut off.